Long strings of railway tank cars are often pulled alongside of elevated platforms for the purpose of loading or unloading the contents of the tanks. These car strings usually are left coupled together, and the tops of the tanks carried by the cars generally need to be accessed by workers. This worker access typically is effected via a fold-down ramp or gangway. In accessing the tops of rolling stock (tank trucks, tank railroad cars, etc.), a gangway is lowered from the elevated platform to allow workers to move cargo between the platform and the top of the rolling stock. These gangways include cantilevers that usually carry a protective enclosure (aka cage) added to the outboard end to provide fall protection while the worker is on top of the rolling stock. Examples of these gangways are disclosed in U.S. Pat. Nos. 4,679,657; 5,042,612; 5,392,878; 7,140,467; 7,216,741 and 8,015,647, the disclosures of which being hereby incorporated herein for all purposes by this reference.
Because of variations in the lengths of railway tank cars, variations in the configurations of the tops of railway tank cars and operator error in positioning the railway tank cars relative to the platform, the gangways often are mounted on tracks that enable the gangway to slide along the length of the platform and thereby assume different positions with respect to the tops of the railway tank cars. An example of a track-mounted gangway is disclosed in U.S. Patent Application Publication No. 2012-0045274, the disclosure of which being hereby incorporated herein for all purposes by this reference.
Depending on how the string of cars is spotted, the length of track required to position the gangways along the length of the elevated platform can become quite large. The string of railway transport cars is usually spotted from one end of the string of cars or from the middle of the string of cars. The farther the car is from the spotting origin, the longer the length of track that the gangway must traverse in order to become properly positioned to allow the worker to access the top of the tank.
A self-closing gate provides access to the gangway when the gangway is moved opposite the opening to the car. Currently, side rails with the gates are bolted or welded on at specific locations of the elevated platform based on current anticipated needs. However, changes in lengths of cars and car configurations can result in additional track being needed than what was originally allowed for. Additionally, the relative locations of the self-closing gates and the fixed sections of side rail on each side of the platform may need to be changed in order to accommodate the different lengths of cars and different car configurations.
Emergency ladders often are used on these long platforms, and each emergency ladder is provided with its own self-closing gate that in turn provides access to the ladder from the elevated platform. Thus, to accommodate the different lengths of cars and different car configurations, the relative locations of the emergency ladder and its associated self-closing gate also may need to be changed so that it does not block movement of the gangway along the track in the platform.
If changed circumstances require reconfiguring the locations of each gangway and its self-closing gate as well as any emergency ladders and associated self-closing gate along the length of the elevated loading platform, effecting these changes poses problems of disassembly and re-assembly and the time and man-hours associated with completing these tasks.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate at least one presently preferred embodiment of the invention as well as some alternative embodiments. These drawings, together with the written description, serve to explain the principles of the invention but by no means are intended to be exhaustive of all of the possible manifestations of the invention.